Light emitting device and projector

ABSTRACT

A light emitting device includes a first layer that generates light by injection current and forms a waveguide for the light, and an electrode that injects the current into the first layer, wherein the waveguide has a first region, a second region, and a third region, the first region and the second region connect at a first reflection part, the first region and the third region connect at a second reflection part, the second region and the third region extend to an output surface, a longitudinal direction of the first region is parallel to the output surface, and a first light output from the second region at the output surface and a second light output from the third region at the output surface are output in parallel to one another.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation patent application of U.S. application Ser. No.13/407,248 filed Feb. 28, 2012, which claims priority to Japanese PatentApplication No. 2011-051570 filed Mar. 9, 2011 all of which areexpressly incorporated by reference herein in their entireties.

BACKGROUND

1. Technical Field

The present invention relates to a light emitting device and aprojector.

2. Related Art

A super luminescent diode (hereinafter, also referred to as “SLD”) is asemiconductor light emitting device that can output several hundreds ofmilliwatts similar to a semiconductor laser, while exhibiting abroadband spectrum and thus being incoherent similar to a typical lightemitting diode.

An SLD is sometimes used as a light source of a projector. To realize alight source having high power and small etendue, it is desirable thatlight beams output from plural gain regions travel in the samedirection. In JP-A-2010-3833, by combining a gain region having a linearshape and a gain region having a flexed shape via a reflection surface,light beams output from light output parts (light emitting areas) of thetwo gain regions travel in the same direction.

To reduce loss of an optical system and reduce the number of opticalcomponents, a projector that can perform light collimation and uniformillumination simultaneously by providing a light emitting deviceimmediately below a light valve and using a lens array, has beenproposed. In this type of projector, however, it is necessary to providelight output parts according to intervals of the lens array.

In the technology described in JP-A-2010-3833, it is difficult toarrange plural light output parts at distances according to various lensarrays with different intervals, and the technology is not applicable tothe projector of the above described type.

SUMMARY

An advantage of some aspects of the invention is to provide a lightemitting device that may be applied to a projector in which distancesbetween plural light output parts may be made larger and a lightemitting device is provided immediately below a light valve. Anotheradvantage of some aspects of the invention is to provide a projectorhaving the light emitting device.

A light emitting device according to an aspect of the invention includesa first layer that generates light by injection current and forms awaveguide for the light, a second layer and a third layer that sandwichthe first layer and suppress leakage of the light, and an electrode thatinjects the current into the first layer, wherein the waveguide has afirst region having a belt-like (elongated) linear shape, a belt-likesecond region, and a belt-like third region, the first region and thesecond region connect at a first reflection part provided at a firstside surface of the first layer, the first region and the third regionconnect at a second reflection part provided at a second side surface ofthe first layer different from the side surface on which the firstreflection part is provided, the second region and the third regionconnect at a third side surface of the first layer which is an outputsurface that is different from the first and second side surfaces, alongitudinal direction of the first region is parallel to the outputsurface, and a first light output from the second region at the outputsurface and a second light output from the third region at the outputsurface are output in parallel.

According to the light emitting device, for example, as compared to thecase where the first region is not parallel to the output surface,distances between the light output parts may be made larger withoutincreasing the total length of the first region, the second region, andthe third region. That is, the distances between the light output partsmay be made larger while the device lengths in the directionperpendicular to the light output surfaces are downsized. As such, agreat amount of current is not necessary and electrical powerconsumption may be suppressed. Further, resources are not wasted and themanufacturing cost may be suppressed.

In the light emitting device according to the aspect of the invention,the output surface may have a reflectance lower than a reflectance ofthe first reflection part and the second reflection part in a wavelengthrange of the light generated in the first layer.

According to the light emitting device, the distances between the plurallight output parts may be made larger.

In the light emitting device according to the aspect of the invention,the first region and the second region may be tilted at a first anglewith respect to a perpendicular of the first side surface as seen from astacking direction of the first layer, and the second layer, the firstregion and the third region may be tilted at a second angle with respectto a perpendicular of the second side surface as seen from the stackingdirection of the first layer, and the second layer, and the first angleand the second angle are equal to or more than a critical angle.

According to the light emitting device, the first reflection part andthe second reflection part may totally reflect the light generated inthe first region, the second region, and the third region. Therefore,light loss in the first reflection part and the second reflection partmay be suppressed and light may efficiently be reflected.

In the light emitting device according to the aspect of the invention,the second region and the third region may extend to the output surfacein the same direction as seen from a stacking direction of the firstlayer, and the second layer.

According to the light emitting device, the distances between the plurallight output parts may be made larger.

In the light emitting device according to the aspect of the invention,the second region and the third region may be tilted with respect to aperpendicular of the output surface and extend to the output surface asseen from the stacking direction of the first layer, and the secondlayer.

According to the light emitting device, it may be possible to preventmultiple reflections of the light generated in the first region, thesecond region, and the third region. As a result, it may be possible toprevent the formation of a direct resonator, and laser oscillation ofthe light generated in the first region, the second region, and thethird region may be suppressed.

In the light emitting device according to the aspect of the invention,the second region and the third region may be parallel to aperpendicular of the output surface and extend to the output surface asseen from the stacking direction of the first layer, and the secondlayer.

According to the light emitting device, the design of a downstreamoptical system may be made easier.

In the light emitting device according to the aspect of the invention,the second region may have a linear first part and a linear second part,the third region may have a linear third part and a linear fourth part,the first part and the second part may connected at a third reflectionpart provided on a fourth side surface of the first layer that isdifferent from the first side surface, the second side surface, and theoutput surface, and the third part and the fourth part may connected ata fourth reflection part provided on a fifth side surface of the firstlayer that is different from the first side surface, the second sidesurface, the fourth side surface, and the output surface.

According to the light emitting device, the light generated in the firstregion, the second region, and the third region may be easier to totallyreflect in the first reflection part, the second reflection part, thethird reflection part, and the fourth reflection part.

In the light emitting device according to the aspect of the invention,the output surface may have a reflectance lower than a reflectance ofthe third reflection part and the fourth reflection part in a wavelengthrange of the light generated in the first layer.

According to the light emitting device, the distances between the lightoutput parts may be made larger.

In the light emitting device according to the aspect of the invention,the first part and the second part may be tilted at a third angle withrespect to a perpendicular of the fourth side surface, as seen from thestacking direction of the first layer, and the second layer, the thirdpart and the fourth part may be tilted at a fourth angle with respect toa perpendicular of the fifth side surface as seen from the stackingdirection of the first layer, and the second layer, and the third angleand the fourth angle may be equal to or more than a critical angle.

According to the light emitting device, the third reflection part andthe fourth reflection part may totally reflect the light generated inthe first region, the second region, and the third region. Therefore,light loss in the third reflection part and the fourth reflection partmay be suppressed and light may efficiently be reflected.

In the light emitting device according to the aspect of the invention, alength of the first region may be larger than a length of the secondregion and a length of the third region.

According to the light emitting device, the distances between the lightoutput parts may reliably be made larger.

A light emitting device according to another aspect of the inventionincludes a multilayered structure having a first layer, and second andthird layers that sandwich the first layer; the first layer has a firstgain region, a second gain region, and a third gain region that generateand guide light; the second layer and the third layer are layers thatsuppress leakage of the light generated in the first gain region, thesecond gain region, and the third gain region; the first layer has afirst surface, a second surface, and a third surface forming an outerperimeter shape of the multilayered structure; a reflectance of thefirst surface is lower than a reflectance of the second surface and areflectance of the third surface in a wavelength range of the lightgenerated in the first gain region, the second gain region and the thirdgain region; the first gain region is provided parallel to the firstsurface and extends from the second surface to the third surface as seenfrom a stacking direction of the multilayered structure, the second gainregion overlaps the first gain region at the second surface and extendsfrom the second surface to the first surface, the third gain regionoverlaps the first gain region at the third surface and extends from thethird surface to the first surface, and the second gain region and thethird gain region are separated from each other and tilted at the sameangle and extend to the first surface as seen from the stackingdirection of the multilayered structure.

According to the light emitting device, the distances between the lightoutput parts may be made larger while downsizing is realized.

A projector according to still another aspect of the invention includesthe light emitting device according to the aspect of the invention, amicrolens that collimates light output from the light emitting device, alight modulation device that modulates the light collimated by themicrolens in response to image information, and a projection device thatprojects an image formed by the light modulation device.

According to the projector, alignment of the lens array may besimplified and the light modulation device may be irradiated with gooduniformity.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a plan view schematically showing a light emitting deviceaccording to an embodiment of the invention.

FIG. 2 is a sectional view schematically showing the light emittingdevice according to the embodiment.

FIG. 3 is a sectional view schematically showing a manufacturing processof the light emitting device according to the embodiment.

FIG. 4 is a plan view schematically showing a manufacturing process ofthe light emitting device according to the embodiment.

FIG. 5 is a sectional view schematically showing a manufacturing processof the light emitting device according to the embodiment.

FIG. 6 is a plan view schematically showing a light emitting deviceaccording to a first modified example of the embodiment.

FIG. 7 is a sectional view schematically showing a light emitting deviceaccording to a second modified example of the embodiment.

FIG. 8 is a plan view schematically showing a light emitting deviceaccording to a third modified example of the embodiment.

FIG. 9 schematically shows a projector according to the embodiment.

FIG. 10 schematically shows the projector according to the embodiment.

FIG. 11 schematically shows a light source of the projector according tothe embodiment.

FIG. 12 is a sectional view schematically showing the light source ofthe projector according to the embodiment.

FIG. 13 is a sectional view schematically showing the light source ofthe projector according to the embodiment.

FIG. 14 is a sectional view schematically showing the light source ofthe projector according to the embodiment.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Below, a preferred embodiment of the invention will be explained withreference to the drawings.

1. Light Emitting Device

First, a light emitting device according to the embodiment will beexplained with reference to the drawings. FIG. 1 is a plan viewschematically showing a light emitting device 100 according to theembodiment. FIG. 2 is a sectional view along II-II line of FIG. 1schematically showing the light emitting device 100 according to theembodiment. Note that, in FIG. 1, for convenience, an illustration of asecond electrode 114 is omitted.

Below, the case where the light emitting device 100 is an SLD of anInGaAlP system (red) will be explained. Unlike a semiconductor laser,the SLD can prevent laser oscillation by suppressing the formation of aresonator due to edge reflection. Accordingly, speckle noise may bereduced.

As shown in FIGS. 1 and 2, the light emitting device 100 may include amultilayered structure 120, a first electrode 112, and the secondelectrode 114.

The multilayered structure 120 may have a substrate 102, a second layer104 (also referred to as “first cladding layer 104”), a first layer 106(also referred to as “active layer 106”), a third layer 108 (alsoreferred to as “second cladding layer 108”), a fourth layer 110 (alsoreferred to as “contact layer 110”), and an insulating layer 116.

As the substrate 102, for example, a first conductivity-type (forexample, n-type) GaAs substrate or the like may be used.

The first cladding layer 104 is formed on the substrate 102. As thefirst cladding layer 104, for example, an n-type InGaAlp layer or thelike may be used. Note that, although not illustrated, a buffer layermay be formed between the substrate 102 and the first cladding layer104. As the buffer layer, for example, an n-type GaAs layer, AlGaAslayer, InGaP layer, or the like may be used. The buffer layer mayimprove the crystal quality of layers formed thereon.

The active layer 106 is formed on the first cladding layer 104. Theactive layer 106 is sandwiched between the first cladding layer 104 andthe second cladding layer 108. The active layer 106 has a multiplequantum well (MQW) structure in which three quantum well structures eachincluding an InGaP well layer and an InGaAlP barrier layer, for example,are stacked.

The planar shape of the active layer 106 is the same as the planar shapeof the multilayered structure 120, for example. In the example shown inFIG. 1, the planar shape of the active layer 106 is a hexagonal shapeand has a first surface 131, a second surface 132, a third surface 133,a fourth surface 134, a fifth surface 135, and a sixth surface 136. Thesurfaces 131 to 136 are the surfaces of the active layer 106, do nothave in plane contact with the first cladding layer 104 and the secondcladding layer 108, and form an outer shape of the multilayeredstructure 120. The surfaces 131 to 136 are flat surfaces provided on theside surfaces (side walls) of the active layer 106 as seen from thestacking direction of the multilayered structure 120, in other words, inside surface parts of the multilayered structure 120.

In the example shown in FIG. 1, the surfaces 134, 135 are orthogonal tothe surface 131. The surface 136 is opposed to the surface 131. Thesurface 132 is connected to the surfaces 134, 136 and tilted withrespect to the surface 131. The surface 133 is connected to the surfaces135, 136 and tilted with respect to the surface 131. For example, thesurfaces 131, 134, 135, 136 are formed by cleavage and the surfaces 132,133 are formed by etching.

Parts of the active layer 106 form a first gain region 150, a secondgain region 160, and a third gain region 170. The gain regions 150, 160,170 may generate light and the light may be amplified while propagatingthrough the gain regions 150, 160, 170. That is, the gain regions 150,160, 170 also serve as waveguides for the light generated in the activelayer 106.

The first gain region 150 has a belt-like linear longitudinal shapehaving a predetermined width (a shape having a longitudinal directionand a shorter direction) in a plan view from the stacking direction ofthe multilayered structure 120 as shown in FIG. 1. Further, as seen fromthe stacking direction of the multilayered structure 120 (in the planview), the first gain region 150 is provided so that its longitudinaldirection from the second surface 132 toward the third surface 133 maybe parallel to the first surface 131. The first gain region 150 has afirst end surface 181 provided on the second surface 132 and a secondend surface 182 provided on the third surface 133. Note that thelongitudinal direction of the first gain region 150 is an extensiondirection of a straight line passing through the center of the first endsurface 181 and the center of the second end surface 182 in the planview from the stacking direction of the multilayered structure 120, forexample. Further, the longitudinal direction may be an extensiondirection of a boundary line of the first gain region 150 (and the partexcept the first gain region 150).

Note that “the first gain region 150 is parallel to the first surface131” means that the tilt angle of the first gain region 150 with respectto the first surface 131 is within ±1° in the plan view in considerationof manufacturing variations.

The first gain region 150 is connected to the second surface 132 tiltedat a first angle α1 with respect to a perpendicular line P2 of thesecond surface 132 in the plan view from the stacking direction of themultilayered structure 120. In other words, the longitudinal directionof the belt-like shape of the first gain region 150 has the angle α1with respect to the perpendicular line P2. Further, the first gainregion 150 is connected to the third surface 133 tilted at a secondangle α2 with respect to a perpendicular line P3 of the third surface133. In other words, the longitudinal direction of the belt-like shapeof the first gain region 150 has the angle α2 with respect to theperpendicular line P3.

The length of the first gain region 150 is larger than the length of thesecond gain region 160 and the length of the third gain region 170. Thelength of the first gain region 150 may be equal to or more than the sumof the lengths of the second gain region 160 and the third gain region170. Note that “the length of the first gain region 150” is also adistance between the center of the first end surface 181 and the centerof the second end surface 182. Regarding the other gain regions,similarly, the length is also a distance between the centers of two endsurfaces.

The second gain region 160 has, for example, a belt-like linearlongitudinal shape having a predetermined width from the second surface132 to the first surface 131 in the plan view from the stackingdirection of the multilayered structure 120. The second gain region 160has a third end surface 183 provided on to the second surface 132 and afourth end surface 184 provided on the first surface 131. Note that “thelongitudinal direction of the second gain region 160” is an extensiondirection of a straight line passing through the center of the third endsurface 183 and the center of the fourth end surface 184 in the planview from the stacking direction of the multilayered structure 120, forexample. Further, the longitudinal direction may be an extensiondirection of a boundary line of the second gain region 160 (and the partexcept the second gain region 160). The third end surface 183 of thesecond gain region 160 overlaps with the first end surface 181 of thefirst gain region 150 on the second surface 132. In the illustratedexample, the first end surface 181 and the third end surface 183completely overlap.

The second gain region 160 is connected to the second surface 132 tiltedat the first angle α1 with respect to the perpendicular line P2 in theplan view from the stacking direction of the multilayered structure 120.In other words, the longitudinal direction of the second gain region 160has the angle α1 with respect to the perpendicular line P2. That is, theangle of the first gain region 150 with respect to the perpendicularline P2 and the angle of the second gain region 160 with respect to theperpendicular line P2 are the same in the range of manufacturingvariations. The first angle α1 is an acute angle and equal to or morethan the critical angle. As such, the second surface 132 may totallyreflect the light generated in the gain regions 150, 160, 170. Note that“the angle of the first gain region 150 with respect to theperpendicular line P2 and the angle of the second gain region 160 withrespect to the perpendicular line P2 are the same” means that they havean angle difference within about ±2°, for example, in consideration ofmanufacturing variations of etching or the like.

The second gain region 160 is connected to the first surface 131 tiltedat an angle β with respect to a perpendicular line P1 of the firstsurface 131 in the plan view from the stacking direction of themultilayered structure 120. In other words, the longitudinal directionof the second gain region 160 has the angle β with respect to theperpendicular line P1. The angle β is an acute angle less than thecritical angle. Note that the second gain region 160 may be parallel tothe perpendicular line P1 of the first surface 131 (β=0°).

The third gain region 170 has, for example, a belt-like linearlongitudinal shape having a predetermined width from the third surface133 to the first surface 131 in the plan view from the stackingdirection of the multilayered structure 120. That is, the third gainregion 170 has a fifth end surface 185 provided on to the third surface133 and a sixth end surface 186 provided on the first surface 131. Notethat “the longitudinal direction of the third gain region 170” is anextension direction of a straight line passing through the center of thefifth end surface 185 and the center of the sixth end surface 186 in theplan view from the stacking direction of the multilayered structure 120,for example. Further, the longitudinal direction may be an extensiondirection of a boundary line of the third gain region 170 (and the partexcept the third gain region 170). The fifth end surface 185 of thethird gain region 170 overlaps with the second end surface 182 of thefirst gain region 150 on the third surface 133. In the illustratedexample, the second end surface 182 and the fifth end surface 185completely overlap.

The second gain region 160 and the third gain region 170 are separatedfrom each other. In the example shown in FIG. 1, the fourth end surface184 of the second gain region 160 and the sixth end surface 186 of thethird gain region 170 are separated at a distance D.

The third gain region 170 is connected to the third surface 133 tiltedat the second angle α2 with respect to the perpendicular line P3 in theplan view from the stacking direction of the multilayered structure 120.In other words, the longitudinal direction of the third gain region 170has the angle α2 with respect to the perpendicular line P3. That is, theangle of the first gain region 150 with respect to the perpendicularline P3 and the angle of the third gain region 170 with respect to theperpendicular line P3 are the same in the range of manufacturingvariations. The second angle α2 is an acute angle and equal to or morethan the critical angle. As such, the third surface 133 may totallyreflect the light generated in the gain regions 150, 160, 170. Note that“the angle of the first gain region 150 with respect to theperpendicular line P3 and the angle of the third gain region 170 withrespect to the perpendicular line P3 are the same” means that they havean angle difference within about ±2°, for example, in consideration ofmanufacturing variations of etching or the like.

The third gain region 170 is connected to the first surface 131 tiltedat the angle β with respect to the perpendicular line P1 in the planview from the stacking direction of the multilayered structure 120. Inother words, the longitudinal direction of the third gain region 170 hasthe angle β with respect to the perpendicular line P1. That is, thesecond gain region 160 and the third gain region 170 are connected tothe first surface 131 and tilted at the same angle so as to be parallelto each other in the plan view. More specifically, the longitudinaldirection of the second gain region 160 and the longitudinal directionof the third gain region 170 are parallel to each other. As such, alight 20 output from the fourth end surface 184 and a light 22 outputfrom the sixth end surface 186 may travel in the same direction. The endsurfaces 184, 186 may serve as light output parts (light emittingareas). Note that the third gain region 170 may be parallel to theperpendicular line P1 of the first surface 131 (β=0°).

As described above, by setting the angles α1, α2 equal to or more thanthe critical angle and the angle β less than the critical angle,reflectance of the first surface 131 may be made lower than reflectanceof the second surface 132 and reflectance of the third surface 133. Thatis, the first surface 131 may serve as a light output surface and thefourth end surface 184 and the sixth end surface 186 provided on theoutput surface may serve as light output parts (light emitting areas)that output light generated in the gain regions 150, 160, 170. Thesecond surface 132 and the third surface 133 may serve as reflectionsurfaces and the first end surface 181 and the third end surface 183provided on the reflection surface may serve as a first reflection part(a first reflection area) that reflects the light generated in the gainregions 150, 160, 170. Similarly, the second end surface 182 and thefifth end surface 185 provided on the reflection surface may serve as asecond reflection part (a second reflection area) that reflects thelight generated in the gain regions 150, 160, 170.

Note that, although not illustrated, for example, the first surface 131may be covered by an antireflection film and the second surface 132 andthe third surface 133 may be covered by reflection films. As such, evenwhen incident angles, refractive indices, and the like may not satisfythe total reflection condition, the reflectance of the first surface 131in the wavelength band of the light generated in the gain regions 150,160, 170 may be made lower than that of the second surface 132 and thethird surface 133. Further, since the first surface 131 is covered bythe antireflection film, direct multiple reflections of the lightgenerated in the gain regions 150, 160, 170 between the fourth endsurface 184 and the sixth end surface 186 may considerably be reduced.As a result, it may be possible to prevent formation of a directresonator, and laser oscillation of the light generated in the gainregions 150, 160, 170 may be suppressed. As the reflection film and theantireflection film, SiO₂ layers, Ta₂O₅ layers, Al₂O₃ layers, TiNlayers, TiO₂ layers, SiON layers, SiN layers, multilayer films of them,or the like may be used. Further, higher reflectance may be obtainedusing DBR (Distributed Bragg Reflector) formed by etching the part ofthe multilayered structure 120 outside the surfaces 132, 133.

Furthermore, the angle β may be set to an angle larger than 0°. As such,it may be possible to prevent direct multiple reflections of the lightgenerated in the gain regions 150, 160, 170 between the fourth endsurface 184 and the sixth end surface 186. As a result, it may bepossible to prevent formation of a direct resonator, and laseroscillation of the light generated in the gain regions 150, 160, 170 maybe suppressed or prevented.

The second cladding layer 108 is formed on the active layer 106 as shownin FIG. 2. As the second cladding layer 108, for example, a secondconductivity-type (for example, p-type) InGaAlP layer or the like may beused.

For example, the p-type second cladding layer 108, the active layer 106not doped with impurity, and the n-type first cladding layer 104 form apin diode. Each of the first cladding layer 104 and the second claddinglayer 108 is a layer having a larger forbidden band gap and a lowerrefractive index than those of the active layer 106. The active layer106 has a function of generating light and amplifying and guiding thelight. The first cladding layer 104 and the second cladding layer 108sandwich the active layer 106 and have a function of confining injectedcarriers (electrons and holes) and light (suppressing leakage of light).

In the light emitting device 100, when a forward bias voltage of the pindiode is applied between the first electrode 112 and the secondelectrode 114 (when a current is injected), the gain regions 150, 160,170 are produced in the active layer 106 and recombination of electronsand holes occurs in the gain regions 150, 160, 170. Light is generatedby the recombination. Starting from the generated light, stimulatedemission occurs and the intensity of the light is amplified within thegain regions 150, 160, 170.

For example, as shown in FIG. 1, the light generated in the second gainregion 160 and traveling toward the second surface 132 side is amplifiedwithin the second gain region 160, and then reflected by the secondsurface 132 (end surfaces 181, 183) and travels in the first gain region150 toward the third surface 133. Then, the light is further reflectedby the third surface 133 (end surfaces 182, 185), travels in the thirdgain region 170, and is output from the sixth end surface 186 as theoutput light 22. Concurrently, the intensity of the light is alsoamplified within the gain regions 150, 170. Similarly, the lightgenerated in the third gain region 170 and traveling toward the thirdend surface 133 side is amplified within the third gain region 170, andthen reflected by the third surface 133 and travels in the first gainregion 150 toward the second surface 132. Then, the light is furtherreflected by the second surface 132, travels in the second gain region160, and is output from the fourth end surface 184 as the output light20. Concurrently, the intensity of the light is also amplified withinthe gain regions 150, 160.

Note that the light generated in the second gain region 160 includeslight directly output from the fourth end surface 184 as the outputlight 20. Similarly, the light generated in the third gain region 170includes light directly output from the sixth end surface 186 as theoutput light 22. This light is similarly amplified in the respectivegain regions 160, 170.

The contact layer 110 is formed on the second cladding layer 108 asshown in FIG. 2. The contact layer 110 may have ohmic contact with thesecond electrode 114. The upper surface 113 of the contact layer 110 maybe a contact surface between the contact layer 110 and the secondelectrode 114. As the contact layer 110, for example, a p-type GaAslayer may be used.

The contact layer 110 and part of the second cladding layer 108 maycompose a columnar part 111. The planar shape of the columnar part 111is the same as the planar shapes of the gain regions 150, 160, 170 asseen from the stacking direction of the multilayered structure 120. Thatis, the planar shape of the upper surface 113 of the contact layer 110may be the same as the planar shapes of the gain regions 150, 160, 170.For example, current channels between the electrodes 112, 114 aredetermined by the planar shape of the columnar part 111 and, as aresult, the planar shapes of the gain regions 150, 160, 170 aredetermined. Note that, although not illustrated, the side surface of thecolumnar part 111 may be inclined.

The insulating layer 116 may be formed at sides of the columnar part 111on the second cladding layer 108. The insulating layer 116 may be incontact with the side surfaces of the columnar part 111. The uppersurface of the insulating layer 116 may be continuous with the uppersurface 113 of the contact layer 110, for example. As the insulatinglayer 116, for example, a SiN layer, an SiO₂ layer, an SiON layer, anAl₂O₃ layer, a polyimide layer, or the like may be used.

When the above described material is used for the insulating layer 116,the current between the electrodes 112, 114 may flow in the columnarpart 111 sandwiched between the insulating layers 116. The insulatinglayer 116 may have a smaller refractive index than the refractive indexof the second cladding layer 108. In this case, the effective refractiveindex of the vertical section of the part in which the insulating layer116 is formed is smaller than the effective refractive index of thevertical section of the part in which the insulating layer 116 is notformed, i.e., the part in which the columnar part 111 is formed. Assuch, in the planar direction, the light may efficiently be confinedwithin the gain regions 150, 160, 170. Note that, although notillustrated, the insulating layer 116 may not be provided. In this case,an air surrounding the columnar part 111 may function as the insulatinglayer 116.

The first electrode 112 is formed on the entire lower surface of thesubstrate 102. The first electrode 112 may be in contact with a layerthat has ohmic contact with the first electrode 112 (the substrate 102in the illustrated example). The first electrode 112 is electricallyconnected to the first cladding layer 104 via the substrate 102. Thefirst electrode 112 is one electrode for driving the light emittingdevice 100. As the first electrode 112, for example, an electrode formedby stacking a Cr layer, an AuGe layer, a Ni layer, and an Au layer inthis order from the substrate 102 side may be used.

Note that a second contact layer (not shown) may be provided between thefirst cladding layer 104 and the substrate 102, the second contact layermay be exposed by dry etching or the like from the opposite side to thesubstrate 102, and the first electrode 112 may be provided on the secondcontact layer. As such, a single-sided electrode structure may beobtained. This configuration is especially advantageous when thesubstrate 102 is insulative.

The second electrode 114 is formed in contact with the upper surface 113of the contact layer 110. Further, the second electrode 114 may beformed on the insulating layer 116 as shown in FIG. 2. The secondelectrode 114 is electrically connected to the second cladding layer 108via the contact layer 110. The second electrode 114 is the otherelectrode for driving the light emitting device 100. As the secondelectrode 114, for example, an electrode formed by stacking a Cr layer,an AuZn layer, and an Au layer in this order from the contact layer 110side may be used.

So far, the case of the InGaAlP system has been explained as an exampleof the light emitting device 100 according to the embodiment, and anymaterial system that can form a gain region may be used for the lightemitting device 100. For example, a semiconductor material of an AlGaNsystem, a GaN system, an InGaN system, a GaAs system, an AlGaAs system,an InGaAs system, an InP system, an InGaAsP system, a GaInNAs system, aZnCdSe system, or the like may be used.

The light emitting device 100 according to the embodiment may be appliedto a light source of a projector, a display, an illumination device, ameasurement device, or the like, for example.

The light emitting device 100 according to the embodiment has thefollowing characteristics, for example.

According to the light emitting device 100, the first gain region 150 isprovided from the second surface 132 to the third surface 133 parallelto the first surface 131 on which the light output parts 184, 186 areformed. Accordingly, for example, as compared to the case where thefirst gain region is not parallel to the first surface, distancesbetween the light output parts may be made larger without increasing thetotal length of the gain region. That is, the distances between theplural light output parts may be made larger while the device length inthe direction perpendicular to the light output surface is made smaller.As such, in the light emitting device 100, a great amount of current isnot necessary and electrical power consumption may be suppressed.Further, resources are not wasted and the manufacturing cost may besuppressed. More specifically, in the light emitting device 100, thedistance D between the light output parts 184, 186 may be set equal toor more than 0.262 mm and less than 3 mm, the angle β may be set equalto or less than 5° (including 0°), and the entire lengths of the gainregions 150, 160, 170 may be set equal to or more than 1.5 mm and equalto or less than 3 mm.

For example, when the entire length of the gain region becomes larger,generally, higher power may be realized, however, a great amount ofcurrent is necessary to obtain the so-called population inversion and,as a result, higher efficiency may not be realized unless the device isused unnecessarily higher light output. That is, with light output lessthan the predetermined light output, the efficiency is deteriorated.Further, when the entire length of the gain region becomes larger, thearea of the entire device becomes larger, and problems of wastedresources, rising manufacturing costs, and the like arise. In the lightemitting device 100 according to the embodiment, these problems may beavoided.

According to the light emitting device 100, the first gain region 150and the second gain region 160 are connected to the second surface 132and may be tilted at the first angle α1 with respect to theperpendicular line P2 of the second surface 132, and the first gainregion 150 and the third gain region 170 are connected to the thirdsurface 133 and may be tilted at the second angle α2 with respect to theperpendicular line P3 of the third surface 133. The angles α1, α2 may beequal to or more than the critical angle. Accordingly, the surfaces 132,133 may totally reflect the light generated in the gain regions 150,160, 170. Therefore, in the light emitting device 100, light loss on thesurfaces 132, 133 (the end surfaces 181, 183 and the end surfaces 182,185) may be suppressed and the light may efficiently be reflected.Further, the process of forming the reflection films on the surfaces132, 133 is not necessary, and the manufacturing cost and the materialsand resources used for manufacturing the films may be reduced.

According to the light emitting device 100, the length of the first gainregion 150 may be made larger than the length of the second gain region160 and the length of the third gain region 170. As such, the distance Dbetween the light output parts 184, 186 may reliably be made larger.

2. Manufacturing Method of Light Emitting Device

Next, a manufacturing method of the light emitting device according tothe embodiment will be explained with reference to the drawings. FIG. 3is a sectional view schematically showing a manufacturing process of thelight emitting device 100 according to the embodiment corresponding toFIG. 2. FIG. 4 is a plan view schematically showing a manufacturingprocess of the light emitting device 100 according to the embodimentcorresponding to FIG. 1. FIG. 5 is a sectional view schematicallyshowing a manufacturing process of the light emitting device 100according to the embodiment corresponding to FIG. 2.

As shown in FIG. 3, on the substrate 102, the first cladding layer 104,the active layer 106, the second cladding layer 108, and the contactlayer 110 are epitaxially grown in this order. As the growth method, forexample, an MOCVD (Metal Organic Chemical Vapor Deposition) method, anMBE (Molecular Beam Epitaxy) method, or the like may be used.

As shown in FIG. 4, the contact layer 110, the second cladding layer108, the active layer 106, the first cladding layer 104, and thesubstrate 102 are patterned, and the second surface 132 and the thirdsurface 133 are formed. The patterning is performed usingphotolithography and etching, for example. Note that, although notillustrated, as long as the second surface 132 and the third surface 133of the active layer 106 are exposed, parts of the cladding layer 104 andthe substrate 102 are not necessarily patterned. Further, the surfaces134, 135, 136 may be formed at the same time with the surfaces 132, 133using photolithography and etching, but they may also be formed bycleavage or the like after fabrication of the columnar part 111 and theelectrodes 112, 114, which will be described later.

As shown in FIG. 5, the contact layer 110 and the second cladding layer108 are patterned. Through the process, the columnar part 111 may beformed.

As shown in FIG. 2, the insulating layer 116 is formed to cover the sidesurfaces of the columnar part 111. Specifically, first, an insulatingmember (not shown) is deposited on the second cladding layer 108(including the contact layer 110) by a CVD (Chemical Vapor Deposition)method, a coating method, or the like, for example. Then, the uppersurface 113 of the contact layer 110 is exposed using etching or thelike, for example. Through the above described processes, the insulatinglayer 116 may be formed.

Then, the second electrode 114 is formed on the contact layer 110 and onthe insulating layer 116. Then, the first electrode 112 is formed on thelower surface of the substrate 102. The first electrode 112 and thesecond electrode 114 are formed by vacuum evaporation, for example. Notethat the order of formation of the first electrode 112 and the secondelectrode 114 is not particularly limited.

Through the above described processes, the light emitting device 100according to the embodiment may be manufactured.

According to the manufacturing method of the light emitting device 100,the light emitting device 100 in which the distances of the light outputparts may be made larger while downsizing is realized may be obtained.

3. Modified Examples of Light Emitting Device

Next, light emitting devices according to modified examples of theembodiment will be explained with reference to the drawings. Below, inthe light emitting devices according to modified examples of theembodiment, the same signs are assigned to the members having the samefunctions as those of the light emitting device 100 according to theembodiment, and a detailed explanation will be omitted.

3.1. Light Emitting Device According to the First Modified Example

First, a light emitting device according to the first modified exampleof the embodiment will be explained with reference to the drawings. FIG.6 is a plan view schematically showing a light emitting device 200according to the first modified example of the embodiment. Note that, inFIG. 6, for convenience, illustration of the second electrode 114 isomitted.

In the example of the light emitting device 100, as shown in FIG. 1, thesecond gain region 160 has been the belt-like linear longitudinal shapeprovided from the second surface 132 to the first surface 131.Similarly, the third gain region 170 has been the belt-like linearlongitudinal shape provided from the third surface 133 to the firstsurface 131. On the other hand, in the light emitting device 200, asshown in FIG. 6, the second gain region 160 is provided from the secondsurface 132 to the first surface 131 via the fourth surface 134, and thethird gain region 170 is provided from the third surface 133 to thefirst surface 131 via the fifth surface 135. In the light emittingdevice 200, the fourth surface 134 and the fifth surface 135 are tiltedwith respect to the first surface 131 in the plan view from the stackingdirection of the multilayered structure 120. The surfaces 134, 135 areformed by etching, for example.

More specifically, the second gain region 160 includes a first gain part162 having a belt-like linear longitudinal shape with a predeterminedwidth from the second surface 132 to the fourth surface 134 and a secondgain part 164 having a belt-like linear longitudinal shape with apredetermined width from the fourth surface 134 to the first surface131.

The first gain part 162 has a third end part 183 provided on the secondsurface 132 and a seventh end surface 187 provided on the fourth surface134. The second gain part 164 has an eighth end surface 188 provided onthe fourth surface 134 and a fourth end surface 184 provided on thefirst surface 131. The seventh end surface 187 and the eighth endsurface 188 completely overlap on the fourth surface 134, for example.In other words, the first gain part 162 and the second gain part 164 areconnected on the fourth surface 134 (the end surfaces 187, 188). Thefourth surface 134 (the end surfaces 187, 188) functions as a reflectionsurface (third reflection part: third reflection area). Note that “thelongitudinal direction of the first gain part 162” is an extensiondirection of a straight line passing through the center of the third endsurface 183 and the center of the seventh end surface 187 in the planview from stacking direction of the multilayered structure 120, forexample. Further, the longitudinal direction may be an extensiondirection of a boundary line of the first gain part 162 (and the partexcept the first gain part 162). Similarly, the longitudinal directionof the second gain part 164 is an extension direction of a straight linepassing through the center of the fourth end surface 184 and the centerof the eighth end surface 188 in the plan view from the stackingdirection of the multilayered structure 120, for example. Further, thelongitudinal direction may be an extension direction of a boundary lineof the second gain part 164 (and the part except the second gain part164).

Each of the first gain part 162 and the second gain part 164 isconnected to the fourth surface 134 and tilted at an a third angle α3with respect to a perpendicular line P4 of the fourth surface 134 in theplan view from the stacking direction of the multilayered structure 120.In other words, each of the longitudinal direction of the first gainpart 162 and the longitudinal direction of the second gain part 164 hasthe angle α3 with respect to the perpendicular line P4. The third angleα3 is an acute angle and equal to or more than the critical angle. Assuch, the fourth surface 134 may totally reflect the light generated inthe gain regions 150, 160, 170.

The third gain region 170 includes a third gain part 172 having abelt-like linear longitudinal shape with a predetermined width from thethird surface 133 to the fifth surface 135 and a fourth gain part 174having a belt-like linear longitudinal shape with a predetermined widthfrom the fifth surface 135 to the first surface 131.

The third gain part 172 has a fifth end part 185 provided on the thirdsurface 133 and a ninth end surface 189 provided on the fifth surface135. The fourth gain part 174 has a tenth end surface 190 provided onthe fifth surface 135 and a sixth end surface 186 provided in theconnection part to the first surface 131. The ninth end surface 189 andthe tenth end surface 190 completely overlap on the fifth surface 135,for example. In other words, the third gain part 172 and the fourth gainpart 174 are connected on the fifth surface 135 (the end surfaces 189,190). The fifth surface 135 (the end surfaces 189, 190) functions as areflection surface (fourth reflection part: fourth reflection area).Note that the longitudinal direction of the third gain part 172 is anextension direction of a straight line passing through the center of thefifth end surface 185 and the center of the ninth end surface 189 in theplan view of from the stacking direction the multilayered structure 120,for example. Further, the longitudinal direction may be an extensiondirection of a boundary line of the third gain part 172 (and the partexcept the third gain part 172). Similarly, “the longitudinal directionof the fourth gain part 174” is an extension direction of a straightline passing through the center of the sixth end surface 186 and thecenter of the tenth end surface 190 in the plan view of from thestacking direction the multilayered structure 120, for example. Further,the longitudinal direction may be an extension direction of a boundaryline of the fourth gain part 174 (and the part except the fourth gainpart 174).

Each of the third gain part 172 and the fourth gain part 174 isconnected to the fifth surface 135 and tilted at an a fourth angle α4with respect to a perpendicular line P5 of the fifth surface 135 in theplan view from the stacking direction of the multilayered structure 120.In other words, each of the longitudinal direction of the third gainpart 172 and the longitudinal direction of the fourth gain part 174 hasthe angle α4 with respect to the perpendicular line P4. The fourth angleα4 is an acute angle and equal to or more than the critical angle. Assuch, the fifth surface 135 may totally reflect the light generated inthe gain regions 150, 160, 170.

Each of the second gain part 164 and the fourth gain part 174 is tiltedat the angle β with respect to the perpendicular line P1 of the firstsurface 131 so as to be parallel to each other in the plan view from thestacking direction of the multilayered structure 120. In other words,each of the longitudinal direction of the second gain part 164 and thelongitudinal direction of the fourth gain part 174 has the angle β withrespect to the perpendicular line P1. Note that the angle β may be 0°.

According to the light emitting device 200, as compared to the exampleof the light emitting device 100, the first angle α1 and the secondangle α2 may be set larger. Accordingly, in the light emitting device200, the light generated in the gain regions 150, 160, 170 may be easierto be totally reflected on the second surface 132 and the third surface133.

3.2. Light Emitting Device According to the Second Modified Example

Next, a light emitting device according to the second modified exampleof the embodiment will be explained with reference to the drawings. FIG.7 is a sectional view schematically showing a light emitting device 300according to the second modified example of the embodiment correspondingto FIG. 2.

In the example of the light emitting device 100, as shown in FIG. 2, thewaveguide of the index-guiding type in which light is confined by therefractive index difference provided between the region where theinsulating layer 116 is formed and the region where the insulating layer116 is not formed, i.e., the region where the columnar part 111 isformed and the light is confined has been explained. On the other hand,in the light emitting device 300, a waveguide of the gain-guiding typein which the columnar part 111 is not formed, i.e., the refractive indexdifference is not provided and the gain regions 150, 160, 170 serve aswaveguide regions as they are may be employed as shown in FIG. 7.

That is, in the light emitting device 300, the contact layer 110 and thesecond cladding layer 108 do not compose the columnar part 111, and theinsulating layer 116 is not formed at the sides thereof. The insulatinglayer 116 may be formed on the contact layer 110 except the parts of thegain regions 150, 160, 170. That is, the insulating layer 116 may haveopenings at the gain regions 150, 160, 170 and the upper surface 113 ofthe contact layer 110 may be exposed in the openings. The secondelectrode 114 may be formed on the exposed parts of the contact layer110 and the insulating layer 116.

The upper surface 113 of the contact layer 110 being contact with thesecond electrode 114 has the same planar shape as those of the gainregions 150, 160, 170. In the illustrated example, current channelsbetween the electrodes 112, 114 are determined by the planar shape ofthe contact surface between the second electrode 114 and the contactlayer 110 and, as a result, the planar shapes of the gain regions 150,160, 170 are determined. Note that, although not illustrated, the secondelectrode 114 may not be formed on the insulating layer 116, and insteadmay be formed only on the contact layer 110 at the gain regions 150,160, 170.

According to the light emitting device 300, as in the light emittingdevice 100, the distances between the light output parts may be madelarger while downsizing is realized.

3.3. Light Emitting Device According to the Third Modified Example

Next, a light emitting device according to the third modified example ofthe embodiment will be explained with reference to the drawings. FIG. 8is a plan view schematically showing a light emitting device 400according to the third modified example of the embodiment. Note that, inFIG. 8, for convenience, an illustration of the second electrode 114 isomitted.

In the example of the light emitting device 100, as shown in FIG. 1, onefirst gain region 150, one second gain region 160, and one third gainregion 170 have been provided. On the other hand, in the light emittingdevice 400, as shown in FIG. 8, plural first gain regions 150, pluralsecond gain regions 160, and plural third gain regions 170 arerespectively provided.

That is, the first gain region 150, the second gain region 160, and thethird gain region 170 may form a group of gain regions 450, and, in thelight emitting device 400, plural groups of gain regions 450 areprovided. In the illustrated example, three groups of gain regions 450are provided, however, the number of groups is not particularly limited.

The plural groups of gain regions 450 are arranged in a directionorthogonal to the direction in which the perpendicular line P1 of thefirst surface 131 extends. More specifically, they are arranged so that,in the adjacent groups of gain regions 450, the distance between thesixth end surface 186 of one group of gain regions 450 and the fourthend surface 184 of the other group of gain regions 450 may be D (thedistance between the light output parts). As such, the light 20, 22 mayeasily enter a lens array, which will be described later.

According to the light emitting device 400, higher power may be realizedas compared to the example of the light emitting device 100.

4. Projector

Next, a projector according to the embodiment will be explained withreference to the drawings. FIG. 9 schematically shows a projector 700according to the embodiment. FIG. 10 schematically shows part of theprojector 700 according to the embodiment. Note that, in FIG. 9, forconvenience, a casing forming the projector 700 is omitted, and further,a light source 600 is simplified for illustration. Further, in FIG. 10,for convenience, the light source 600, a lens array 702, and a liquidcrystal light valve 704 are illustrated, and further, the light source600 is simplified for illustration.

The projector 700 includes a red light source 600R, a green light source600G, and a blue light source 600B that output red light, green light,and blue light as shown in FIG. 9. The light sources 600R, 600G, 600Bhave the light emitting devices according to the invention. In thefollowing example, the light sources 600R, 600G, 600B having the lightemitting devices 400 as the light emitting devices according to theinvention will be explained.

FIG. 11 schematically shows the light source 600 of the projector 700according to the embodiment. FIG. 12 is a sectional view along XII-XIIof FIG. 1 schematically showing the light source 600 of the projector700 according to the embodiment.

The light source 600 may have the light emitting devices 400, a base610, and sub-mounts 620 as shown in FIGS. 11 and 12.

The two light emitting devices 400 and the sub-mount 620 may form astructure 630. Plural structures 630 are provided and arranged in thedirection (Y-axis direction) orthogonal to the arrangement direction(X-axis direction) of the end surfaces 184, 186 which are the lightoutput parts of the light emitting devices 400 as shown in FIG. 11. Thestructures 630 may be arranged so that the distance between the lightoutput parts in the X-axis direction and the distance between the lightoutput parts in the Y-axis direction may be equal. As such, the lightoutput from the light emitting devices 400 may easily enter the lensarray 702.

The two light emitting devices 400 forming the structure 630 areprovided with the sub-mount 620 sandwiched in between. In the exampleshown in FIGS. 11 and 12, the two light emitting devices 400 areprovided so that the second electrodes 114 may be opposed via thesub-mount 620. On part of the surface of the sub-mount 620 being contactwith the second electrode 114, for example, wiring is formed. As such,voltages may individually be supplied to the respective plural secondelectrodes 114. As the material of the sub-mount 620, for example,aluminum nitride and aluminum oxide may be cited.

The base 610 supports the structures 630. In the example shown in FIG.12, the base 610 is connected to the first electrodes 112 of the plurallight emitting devices 400. As such, the base 610 may function as acommon electrode of the plural first electrodes 112. As the material ofthe base 610, for example, copper and aluminum may be cited. Althoughnot illustrated, the base 610 may be connected to a heat sink via aPeltier device.

Note that the form of the structure 630 is not limited to the exampleshown in FIGS. 11 and 12. For example, as shown in FIG. 13, two lightemitting devices 400 forming the structure 630 may be provided so thatthe first electrode 112 of one light emitting device 400 and the secondelectrode 114 of the other light emitting device 400 may be opposed viathe sub-mount 620. Alternatively, as shown in FIG. 14, they may beprovided so that the first electrodes 112 of the two light emittingdevices 400 may be a common electrode.

As shown in FIG. 9, the projector 700 further includes lens arrays 702R,702G, 702B and transmissive liquid crystal light valves (lightmodulation devices) 704R, 704G, 704B, and a projection lens (projectiondevice) 708.

The light output from the respective light sources 600R, 600G, 600Benter the respective lens arrays 702R, 702G, 702B. As shown in FIG. 10,the lens array 702 may have flat surfaces 701 that the light 20, 22output from the light output parts 184, 186 enters. Plural flat surfaces701 are provided in correspondence with the plural light output parts184, 186 and arranged at equal distances. Further, the normal lines ofthe flat surfaces 701 are tilted with respect to the optical axes of thelight 20, 22. By the flat surfaces 701, the optical axes of the light20, 22 may be made orthogonal to an irradiated surface 705 of the liquidcrystal light valve 704. Especially, when the angles β formed by thefirst surface 131 and the second and the third gain regions 160, 170 arenot 0°, the light 20, 22 output from the respective light output parts184, 186 are tilted with respect to the perpendicular line P1 of thefirst surface 131, and thus, it is desirable that the flat surfaces 701are provided.

The lens array 702 may have convex curved surfaces 703 at the liquidcrystal light valve 704 side. Plural convex curved surfaces 703 areprovided in correspondence with the plural flat surfaces 701 andarranged at equal distances. The light 20, 22 with optical axesconverted on the flat surfaces 701 are collected (collimated) ortraveling at diffusion angles reduced by the convex curved surfaces 703,and may be superimposed (partially superimposed). As such, the liquidcrystal light valve 704 may be irradiated with good uniformity.

As described above, the lens array 702 may control the optical axes ofthe light 20, 22 output from the light source 600 and integrate thelight 20, 22.

As shown in FIG. 9, the light integrated by the respective lens arrays702R, 702G, 702B enters the respective liquid crystal light valves 704R,704G, 704B. The respective liquid crystal light valves 704R, 704G, 704Brespectively modulate the incident light in response to imageinformation. Then, the projection lens 708 enlarges images formed by theliquid crystal light valves 704R, 704G, 704B and projects them on ascreen (display surface) 710.

Further, the projector 700 may include a cross dichroic prism (colorcombining unit) 706 that combines light output from the liquid crystallight valves 704R, 704G, 704B and guides the light to the projectionlens 708.

The three colors of light modulated by the respective liquid crystallight valves 704R, 704G, 704B enter the cross dichroic prism 706. Theprism is formed by bonding four right angle prisms, and a dielectricmultilayer film that reflects red light and a dielectric multilayer filmthat reflects blue light are provided crosswise on its inner surfaces.By the dielectric multilayer films, the three colors of light arecombined and light representing a color image is formed. Then, thecombined light is projected on the screen 710 by the projection lens 708as a projection system, and the enlarged image is displayed thereon.

According to the projector 700, the light emitting devices 400 that maymake distances between the plural light output parts larger whiledownsizing is realized is provided. Accordingly, in the projector 700,alignment of the lens array 702 may be easy and the liquid crystal lightvalve 704 may be irradiated with good uniformity.

Note that, in the above described example, transmissive liquid crystallight valves have been used as the light modulation devices, however,other light valves than liquid crystal, or reflective light valves maybe used. As the light valves, for example, reflective liquid crystallight valves and digital micromirror devices may be used. Further, theconfiguration of the projection system may appropriately be changeddepending on the type of the light valves employed.

Further, the light source 600 and the lens array 702 may be modularizedin alignment with each other. Furthermore, the light source 600, thelens array 702, and the light valve 704 may be modularized in alignmentwith one another.

In addition, the light source 600 may also be applied to a light sourcedevice of a scanning type image display device (projector) having ameans of scanning light for displaying an image in a desired size on adisplay surface.

The above described embodiments and modified examples are just examples,and the invention is not limited to these. For example, the respectiveembodiments and the respective modified examples may be appropriatelycombined.

The embodiments of the invention have been specifically explained above,and a person skilled in the art could easily understand that manymodifications may be carried out without substantively departing fromthe spirit and effect of the invention. Therefore, these modifiedexamples are included in the range of the invention.

What is claimed is:
 1. An illumination device comprising: a first layerthat generates light by injection current, and forms a waveguide for thelight; a second layer and a third layer that sandwich the first layerand suppress leakage of light; and an electrode that injects the currentinto the first layer, wherein the waveguide has a first region having anelongated shape, an elongated second region, and an elongated thirdregion, the first region and the second region connect at a firstreflection part provided at a first side surface of the first layer, thefirst region and the third region connect at a second reflection partprovided at a second side surface of the first layer different from thefirst side surface, the second region connect at a third side surface ofthe first layer different from the first side surface and the secondside surface, the third region connect at fourth side surface of thefirst layer different from the first side surface and the second sidesurface, a longitudinal direction of the first region has equal to ormore than a critical angle with respect to a perpendicular of the firstreflection part and the second reflection part as seen from the stackingdirection, a longitudinal direction of the second region has equal to ormore than a critical angle with respect to a perpendicular of the firstreflection part as seen from the stacking direction, a longitudinaldirection of the third region has equal to or more than a critical anglewith respect to a perpendicular of the second reflection part as seenfrom the stacking direction.
 2. The illumination device according toclaim 1, a longitudinal direction of the second region has less than acritical angle with respect to a perpendicular of the third side surfaceas seen from the stacking direction, a longitudinal direction of thethird region has less than a critical angle with respect to aperpendicular of the fourth side surface as seen from a stackingdirection.
 3. The illumination device according to claim 1, wherein thethird side surface and fourth side surface has a reflectance that islower than a reflectance of the first reflection part and the secondreflection part in a wavelength range of the light generated in thefirst layer.
 4. The illumination device according to claim 1, whereinthe third side surface and the fourth side surface are same side surfaceof the first layer.
 5. The illumination device according to claim 1,wherein the longitudinal direction of the second region and the thirdregion are parallel as seen from the stacking direction.
 6. The lightemitting device according to claim 1, wherein the second region istilted with respect to a perpendicular of the third side surface as seenfrom the stacking direction, the third region is tilted with respect toa perpendicular of the fourth side surface as seen from the stackingdirection.
 7. The light emitting device according to claim 1, whereinthe second region has a linear first part and a linear second part, thethird region has a linear third part and a linear fourth part, the firstpart and the second part connect at a third reflection part provided ata fifth side surface of the first layer that is different from the firstside surface, the second side surface, the third side surface and thefourth side surface, and the third part and the fourth part connect at afourth reflection part provided at a side surface of the first layerthat is different from the first side surface, the second side surface,the third side surface, the fourth side surface and the fifth sidesurface.
 8. The light emitting device according to claim 7, wherein thethird side surface and fourth side surface has a reflectance that islower than a reflectance of the third reflection part and the fourthreflection part in a wavelength range of the light generated in thefirst layer.
 9. The light emitting device according to claim 7, whereinthe first part and the second part has equal to or more than a criticalangle with respect to a perpendicular of the third reflection part asseen from the stacking direction, the third part and the fourth part hasequal to or more than a critical angle with respect to a perpendicularof the third reflection part as seen from the stacking direction. 10.The light emitting device according to claim 1, wherein a length of thefirst region is larger than a length of the second region and a lengthof the third region.
 11. A projector comprising: the light emittingdevice according to claim 10; a microlens that collimates light outputfrom the light emitting device; a light modulation device that modulatesthe light collimated by the microlens in response to image information;and a projection device that projects an image formed by the lightmodulation device.
 12. A projector comprising: the light emitting deviceaccording to claim 1; a microlens that collimates light output from thelight emitting device; a light modulation device that modulates thelight collimated by the microlens in response to image information; anda projection device that projects an image formed by the lightmodulation device.